Wireless Communication and Sensor Network

The following sections are included:

• Preface
• Committees
• Contents

This paper introduces a simple two-dimensional ray tracing visual tool, Ray-VT, for simulating propagations in the tropospheric environment. It is capable of tracing ray paths through range-dependent refractive conditions as well as arbitrary terrain cases. The fundamental computations are based on the assumption of the constant-gradient of layered refractivity and a small angle approximation to the Snell's Law. The Ray-VT can be used to investigate the effects of ducting propagations and to assess the performances of radar systems. It can also be used as an educational aid for understanding the propagation characteristics in the complex environments.

Multi-antenna receivers were first developed for attitude determination, and have started being used for deformation monitoring in recent years. However, due to its special structure that a receiver needs to connect multiple antennas, the traditional way of using cables to connect multiple antennas with a receiver simultaneously may be unavailable in some scenarios, such as when the baselines between the antennas are too long. Therefore, we designed a new multi-antenna receiver transmission unit called horn antenna based wireless transmission unit, which mainly uses the horn antenna to complete the wireless transmission of signals between the receiver and Global Navigation Satellite System (GNSS) receiving antennas. Experiments on different baselines, different types of receivers, different satellite signals and different environments were conducted to test the proposed wireless transmission unit.

Getting a good time-frequency distribution of frequency hopping (FH) signals is crucial for detecting and tracing the FH signals. In this paper, the theory of the rearrangement of time-frequency distribution is first summarized. Then, the basic principles of detecting the signals using the algorithm of rearrangement of the smooth pseudo Wigner-Ville distribution (RSPWVD) and the algorithm of rearrangement of the Morlet scale chart (RMSC) are analyzed in detail, with their algorithm expressions being given at the same time. The analysis results show that the RMSC algorithm not only has more ideal anti-jamming effects, but can also enhance the time-frequency aggregation of the signal. Thus, the signal parameters are estimated more accurately using the RMSC algorithm. At the end, the computer simulation is shown to test the feasibility and effectiveness of the algorithm.

A new method for the design of elliptical beam reflector antenna is presented in this paper. By means of the basic principles of ring-focus antenna, a circularly symmetric feed and two specially shaped reflectors are used to form an elliptical beam antenna. The gain at center frequency (12GHz) is 37.7dBi with an aperture efficiency of 62.3%. 3dB beam-width in φ=0^o and φ=90^o plane is 2.6^o and 1.4^o, respectively. Ratio of elliptical beam is 1.85. Simulating and testing results match well, which testify the effectiveness of this design method.

For Global Navigation Satellite System (GNSS), adaptive beamforming techniques are critical to interference and multipath mitigation in various applications. The major problems with existing beamforming architectures are their Initial Measurement Unit (IMU) dependence and need for gain/phase calibration. In this paper, we proposed an optimal blind beamforming architecture that could achieve the maximum output signal-to-interference-plus-noise ratio (SINR) in the presence of gain/phase mismatch. The effectiveness of the proposed architecture is verified by theory analysis and simulation results.

Multipath interference, which is difficult to eliminate through the differential method because they are not interrelated in space, affects the positioning accuracy of global navigation satellite systems (GNSS). Binary-offset-carrier (BOC) modulation is widely used in GNSS. The pseudo correlation function (PCF) method employs two special local signals and nonlinear processing to form a no-side-peak function. Due to the nonlinear processing for the autocorrelation function in the PCF method, the analysis is different from the traditional method. This paper analyses the multipath performances of PCF method for the typical BOC signals and compares it with the binary phase-shift keying (BPSK)-like method. The analysis results indicate that the running average multipath error (RAME) of PCF method in most of the intervals is less than that of the BPSK-like method when the parameters are appropriate. Thus, the overall anti-multipath performance of PCF method is better than that of BPSK-like method in some cases.

Narrowband interference can severely degrade the performance of pulse signal detection. This paper presents a simple and efficient suppression scheme with temporal and frequency processing techniques. We implement a stand-alone interference suppressor on field programmable gate array (FPGA) based on digital tuning and 1st-order notch filtering. When a pulse signal along with narrowband interference is detected through spectral measurements, the interference signal is translated to zero frequency using down-converter and filtered out by a simple high-pass infinite impulse response (IIR). The original pulse signal is translated to its previous frequency using corresponding up-converter after alleviating the effects of interference. Furthermore, we deduce the frequency interval between pulse signal and narrowband interference to satisfy interference suppression performance. Experimental results show that the proposed interference suppressor can reduce narrowband interference and detect a pulse signal with acceptable RMS performance.

This paper discusses the Long-Term Evolution (LTE) network architecture and key technologies, discontinuous reception (DRX) mechanisms of different systems and a comparison of the effects of using each DRX mechanism. Research is carried out on DRX mechanisms based on three kinds of optimization algorithms: semi-Markov control model, online learning adaptive DRX mechanisms, and adaptive control sleep cycle of DRX mechanisms. Finally, DRX mechanism of the adaptive control sleep cycle is simulated, and the advantages and disadvantages of the algorithm are analyzed. The results of this paper have good reference value for research into the LTE system.

Reliability and fault tolerance are important metrics for evaluating the performance of Wireless Sensor Network (WSN). Although many WSN protocols have performed well in laboratory and simulation circumstances, the complex environment during actual deployment can lead to some problems, such as system abnormal, communication interruption, packet loss and reliability decline. These make it difficult to debug and perform failure analyses on the system. In this paper we present a new method of injecting faults to WSN artificially. By simulating the scene interference and observing the change of network, we can evaluate the reliability and fault tolerance of the network. We can also find a way to improve the network performance by analyzing the change of network after injection of faults. This system includes fault inject node and failure analysis software. The fault inject node can inject practical faults and interference which the WSN is likely to encounter, and can receive the WSN nodes' data and store them. The failure analysis software can analyze data obtained from the fault inject nodes, and display the topology change to evaluate reliability. Using pairs of WSN node and fault injection performance evaluation system (FIPES) node, we evaluate this system in a five-storey office. This includes the use of FIPES to inject large-scale faults into WSN and monitor the network fault response conditions, thereby verifying the effect of FIPES fault injection. Experimental results show that the FIPES can inject various kinds of faults into WSN effectively, and can evaluate WSN performance metrics such as reliability, packet loss rate etc.

In this paper, we put forward a novel modulation recognition method based on Robust Linear Discriminant Analysis (RLDA). Feature-based modulation recognition methods consist of two steps: feature extraction and classification. In order to simultaneously eliminate the relativity between different features and keep the important identity for classification, we need to search for a best feature subspace in which different modulation can be very well distinguished. RLDA aims to find the projection that maximizes the distance between different classes, while minimizing the distance within the same classes. RLDA also builds a graph incorporating neighborhood information of the data set to preserve the global similarity structure. It is likely that a nearest neighbor search in the subspace will yield similar results to that in the original feature space. Combined with 1-NN nearest-neighbor pattern classifier, the experimental results demonstrate that the proposed method achieves better classification performance compared with other methods.

In this paper, an ultra-wideband LNA for 0.6-6GHz wireless communication systems is designed based on GaAs HEMT technology. Its components are all fully integrated on a 1.25mm×0.99mm single chip. The implemented LNA shows a maximum power gain of 12.318dB with 1dB variation, a NF lower than 2.48dB and VSWRs no more than 2.2. In addition, the achieved highest OIP3 is 36.7dBm at 5GHz and the input P_1dB is better than 5.4dBm. Compared with the performance of LNA in CMOS technology reported by previous studies, the proposed LNA provides the best NF and IIP3.

Modulation recognition is an important issue in cognitive radio research area, however, high recognition precision is usually achieved by relative large number of training data and more various features of digital signal, which call for much more resource. In this paper, a novel high order cumulant vectors is proposed as features for digital signal modulation recognition, which are constructed as features to train support vector machine classifiers for modulation signal recognition. The experimental results shows the proposed approach can get comparative high precision for PSK signal recognition in additive white Gaussian noise channel while using relative small number of training samples, which reduce cost remarkably.

Low density parity check (LDPC) codes perform well when used for error correction and anti-jamming purposes. In digital communication, LDPC codes are used to encrypt binary sequences, improving the anti-jamming ability of the information and reducing the distortion of the decrypted information. In this paper, we first introduce the basic concepts of LDPC codes, followed by an analysis of the encoding and decoding algorithms. Finally, we discuss the results from a simulation experiment in which LDPC codes are used for secure communication. It was shown that the LDPC codes of secure communication system has good security performance and anti-interference ability.

The issue of routing is vitally important in Wireless Mesh Networks. But currently, most routing protocols such as OLSR and AODV cannot make the most of multiple paths between the source site and destination site because of the complexity and the cost. Software Defined Networking(SDN) structure promises to obtain the network configuration effectively, and with a centralized controller, it can deploy fine-grained routing algorithms to make full use of the network resources, while ensuring that the control overhead is acceptable. In this paper, we propose a new approach of SDN-based routing algorithm, or SDNR. We introduce link saturation to SDN, with which the SDN controller can figure out the congested path and reroute the following traffic to another non-congested path, which is the real-time optimal one, to ensure the network throughput. We compare SDNR to classic routing protocols and demonstrate its superiority.

A GA-based method for the design of single feed multi-beam reflectarray antenna with asymmetry radiation pattern is presented in this paper. Using this method, a Ku-band single feed dual-beam reflectarray with 904 elements is designed, simulated and measured. Measured results demonstrate that two beams scan correctly to the designed asymmetry directions and measured gain at 12 GHz is 26.03 dB. Both the 1 dB gain bandwith and 3 dB AR bandwith can cover the frequence band 11.3GHz-12.3GHz.

Concurrent multipath transfer (CMT) in wireless mesh networks (WMNs) offers many advantages and has attracted much attention. As multiple paths are used simultaneously, congestion control in CMT should ensure it shares bandwidth fairly with single-path transfers while providing throughput improvement and congestion balancing. In this paper, we present a new way to precisely evaluate the congestion level of a wireless link for the purpose of adjusting the congestion window. This method uses the congestion level and data rates of multiple paths to achieve a more fine-grained control of the congestion window. Furthermore, increasing of the congestion window is optimized through window decrease, thus achieving the goal of fairness. Simulation results indicate that the proposed algorithm can achieve better throughput performance compared with existing algorithms in wireless mesh networks, while ensuring fairness and congestion balancing.

In this paper, we present a new cascaded structure in a notch filter for detecting multiple complex sinusoids. The notched frequency of each level filter is updated adaptively with a simpler gradient-based algorithm than the one proposed by S. Nishimura. Results from a computer simulation have shown that, as compared to S. Nishimura's cascaded structure, the proposed cascaded structure has close variances of estimated multiple frequencies under conditions of Gaussian noise and a similar performance in tracking both the linear chirp sinusoids and frequency-hopping sinusoids.

Deploying an appropriate number of redundant mobile nodes in wireless sensor networks can greatly improve network performance. The selection of mobile nodes from among redundant ones is, however, key. This paper describes the redundant mobile node selection policy based on least reliance values, which are composed of the node energy consumption model, node dependent model and distributed selection strategy of redundant mobile nodes. When implemented, the results derived show that this policy can not only reduce the alternative failure of mobile nodes, but also improve the network life cycle.

In this paper, we focus on preamble-based time of arrival (TOA) estimation for orthogonal frequency division multiplexing (OFDM) systems in non-line-of-sight (NLOS) environments. Recent development in wireless communication-based positioning systems exploiting TOA methods faces a major challenge for the TOA estimation in NLOS condition. Because of the possible obstruction of the direct path, the signal component from direct propagation can be very weak and therefore, the performance of TOA estimation will be dramatically degraded. An accurate TOA estimation utilizing channel estimation is presented. The proposed approach consists of three stages. First, we obtain coarse integer TOA estimation by correlation detection. Second, Maximum-likelihood criterion is employed in channel impulse response estimation to get the fine integer TOA estimate. We exploit the multipath interference cancellation with channel equalization in frequency domain. Finally, to break the limitation by sampling interval, fractional TOA estimate by linear fit is obtained. Compared with the off-the-shelf method, the simulation results show that our method achieves more precise TOA estimation.

In order to research the system of satellite communication and its new technology in the laboratory, an up-converter and down-converter for S-band is proposed in this paper. A PLL (phase locked loop) frequency synthesizer, an IF (intermediate frequency) AGC (automatic gain control) amplifier, and a coaxial cavity filter is designed based on chip ADF4113. The amplitude-frequency characteristic, phase-frequency characteristic and degree of balance for channels are measured. The measurement results are given. The spurious signal is -70 dBc over the 500 MHz band, and the phase noise is - 80dBc/Hz@1kHz. The amplitude-frequency characteristic and phase-frequency characteristic of uplink and down-link are tested, and verified the feasibility of the scheme.

This paper proposes a promising method of test signal simulation for multi-beam receivers in satellite communication. Based on a mathematical model with M users and N antennas, we present a simulator architecture that has high extensibility, and employ a combination of two NCOs to make up a primary signal simulation unit. Using the proposed method, we demonstrate a real signal simulator with five basic hardware units and a total of 10 signal channels, which can be easily extended by adding some basic hardware units. Finally, the performance of the test signal simulation is tested in the real system.

Antenna phase center offsets (PCO) and phase center variations (PCV) play an important role in high-precision GNSS applications. For the fixed pattern antenna array, the amplitude and phase difference between antennas may cause phase center degrading. In this paper, the effect of amplitude and phase difference on the phase center is studied. The method of computing the PCO and PCV for a given antenna pattern is first described, followed by the calculation of the far-field phase pattern including the amplitude and phase difference for the antenna array. Lastly, the phase center character of a two-element patch antenna array is presented and analyzed as a practical example.

With the widespread application of wireless communication technology, wireless spectrum resource scarcity has become increasingly prominent. A way to efficiently utilize the limited spectrum resource to satisfy increasing mobile traffic is key to the development of wireless communication system in the power industry, especially for the 230MHz TD-LTE network. To this end, spectrum sensing technology has emerged as a promising solution, and this paper thus studies the rational use of the idle spectrum resources collaborative sensing technology to improve spectrum efficiency in the use of the 230MHz frequency band. Results from the application and evaluation of this technology verify its effectiveness, providing a basis for further development of 230MHz band spectrum sharing.

Wireless local area network (LAN) is based on the IEEE 802.11 protocol standard and defines the MAC protocol, which can be used to solve the problem of the sharing of wireless LAN channels between competing nodes. The basic way of accessing the MAC protocol is through the distributed coordination function (DCF), which uses carrier sense multiple access with collision avoidance (CSMA/CA), as well as the Request to Send / Clear to Send (RTS/CTS) mechanism, which reduces frame collisions introduced by avoidable hidden node and exposed node problems. This article discusses the hidden node and exposed node problems. NS2 simulation software is used to study and analyse the hidden node problem, and the results are subsequently analysed so as to determine how they may be applied to improve network performance.

Low power subsampling architecture is proposed in this paper for Internet of Things (IoT) receiver applications. This architecture adopts the passive subsampling mixer and Q-enhanced filter to achieve signal demodulation without extra components. For the 780MHz IoT wireless communication applications, the subsampling receiver can achieve a data rate of 1Mbps with a clock sampling frequency of 40MHz. Finally, the simulation results show that the receivers with a subsampling architecture are more advantageous than others, especially in terms of power consumption and flexibility.

Wireless radio stations still play a very important role in modern communication, especially in disaster areas. This paper presents a polling MAC protocol implementation as well as a performance analysis for an emergency communication networking scheme based on wireless radio stations. We consider the different conditions for the specific type of station and propose the related MAC protocol for data transmission. Using the embedded Markov chain theory and the probability generating function methodology, we not only qualitatively discuss the MAC protocol, but also derive a more precise mathematical description of the networking scheme. The scheme's performance is evaluated using the analytical results and the computer simulations.

This paper presents the design and fabrication of 7-9.4GHz microstrip bandpass filter with stub-loaded quad-mode resonator. Simulated results indicate that the filter with a passband of 7.55-10.25GHz exhibits insertion loss of 0.7-1.52 dB and sharp attenuations of above 40 dB in stopbands. The input and output return losses are no more than -10dB, respectively. Due to fabrication error, the initial measured passband shows frequency shift. The measured results imply that the input and output return losses are lower than -10dB and the insertion loss with a passband ripple of 1dB varies between 1.5dB and 2.4 dB. Filter has a sharp skirt and out-of-band rejection level approaching to 40dB in all desired stopbands.

A fast audio signal segmentation algorithm in a piano audio stream is presented. Audio segmentation is the fundamental step when applying discrimination. The goal of this work is to make a fast and accurate segmentation algorithm of the audio stream. By detecting abrupt changes in audio short-time energy and separating them with appropriate threshold intervals, the single music note is obtained. The results show an effective and accurate algorithm for the musical audio stream segmentation.

Image noise variance estimation is the most important part of the Compressed-Sensing (CS) reconstruction algorithm. Most existing noise variance estimation only process the median of the absolute value of high-frequency coefficient after image sparse transform, without considering the effect of image texture features, sparse transformation type and the sampling rate. The noise variance estimation is thus not precise, hence affecting the estimation of image coefficients, ultimately affecting the quality of the reconstructed image. This paper presents an improved method of noise variance estimation, based on the image texture features, the type of sparse transformation and the joint estimation of image sampling rate. The algorithm is then evaluated. The simulation results show that the new noise variance estimation method increases image quality.

This paper describes a wireless spectral sensing network (WSSN) applied in mushroom workshops, which is capable of measuring the near infrared spectrum and the environmental parameters. With the sensing ability of chemical compositions, the WSSN can be used to provide scientific guidance for mushroom cultivation. As the network's core unit, the spectral sensing node uses, uniquely, a new monolithically integrated multichannel spectral sensor (MCSS). A multichannel integrated narrow-band filter array, an uncooled InGaAs detector array and a readout circuit are integrated into the MCSS. Benefiting from the monolithic design of MCSS, the size and complexity of the spectral sensing node is reduced. A field programmable gate array (FPGA) is used to control the whole measurement process and wireless communication. The discussion in this paper focuses on the design and performance of the spectral sensing node.

Signal detection can be applied to the spectrum sensing, which is a key technology of cognitive radio (CR). The conventional signal detection algorithms calculate the sum of energy in interested frequency band to recognize whether a modulated signal is present or not. However, the noise power level is volatile in different cases, which deteriorates the detection performance. In this paper, we propose a new modulated signal detection algorithm by dividing the analyzed spectrum band into several blocks and then calculating the sum of their energy variances. Numerical results indicate that about 5dB lower signal-to-noise ratio (SNR) is needed to detect modulated signal in provided algorithm compared with traditional method.

Legacy IEEE 802.11 does not efficiently support multicast transmissions. To cope with the increasing demand for multicast, which is mainly required to deliver multimedia traffic, the IEEE 802.11aa Task Group has recently standardized new mechanisms for allowing efficient and robust transmission of multicast flows in wireless local area networks (WLAN). However, the standard allows the use of different mechanisms for this purpose, and leaves open the choice of which one to use for a given scenario. In this paper, we present an analytical model for evaluating the performance of the mechanisms included in the 802.11aa standard and then compare their performance. Our analysis shows that there is no absolute winner out of these mechanisms and performance strongly depends on the scenario. Building on our model, we then propose a novel algorithm that selects the best multicast mechanism to use as a function of the scenario conditions. Our results are validated by extensive simulations.

This paper mainly studies the interference suppression of Direct Sequence Spread Spectrum (DSSS) systems. The visual simulation tool Simulink provided by Matlab is used to build the transmitter and receiver modules of a DSSS communication system, and narrow-band interferences in different carrier frequencies and amplitudes are added to the AWNG channel. The relationship between the bit error rate (BER), signal-to-noise ratio (SNR) and spreading gain of the DSSS system is researched using every waveform and spectrum transformation diagram in the transmission process. When the narrow-band interference oversteps the tolerance of the DSSS system, we can use the adaptive filters such as LMS (Least Mean Square) filter and RLS (Recursive Least Square) filter to improve suppression of narrow-band interference. The simulation confirmed that the adaptive filter has a good effect on narrow-band interference suppression. The RLS Filter's algorithm is complex, so its simulation time is long. The LMS filter's convergence speed is slow.

Compared to many other communication channels, the powerline channel is characterized by time-varying non-additive noise, severe attenuation and multi-path propagation. Due to the complicated channel properties, the spectrum resource should be dynamically managed, which is of great importance in the design of high-speed PLC metering system. In this paper, we propose a novel fair-based dynamic spectrum management (FDSM) algorithm, which is able to adapt the real-time PLC channel in hybrid broadband-narrowband PLC metering system. Under a given PLC channel, the algorithm first allocates optimal subcarriers for all user equipments (UE) according to the sub-channel attenuation. Then, depending on the UE's required minimum transmission rate and current rate, a weighted factor is employed to achieve rate fairness for all UEs. Compared to the typical Round Robin (RR) algorithm and Maximum Sum Rate (MSR) algorithm, the proposed algorithm attains a better trade-off between network throughput and UE fairness. Simulations demonstrate the effectiveness and advantages of the proposed algorithm.

The VLF radio wave propagation is usually treated as a waveguide problem. It should be noted that many of the parameters that describe the boundaries of the earth-ionosphere waveguide are not known with great accuracy over all regions and times. In order to know the effect of underwater platform receiving in corresponding region and time, this paper makes use of the waveguide mode theory to predict the field strength of VLF radio. It can offer the service of propagation environment for the system to adjust the variable parameters or abstain from propagation attenuation. Then we will able to make the system performance matching the channel character and advancing the effects of VLF communication.

We demonstrate a method, sub-intensity pattern stitching, to extend the amplitude measurement range of wavefront in phase retrieval. An algorithm based on least square to stitch is presented. An experimental setup used to measure a spherical mirror with 100mm diameter and 650mm radius using this stitching method is arranged. The stitching results and corresponding interferometer results are in excellent agreement, which promises the validity of this method.

The issue of direction of arrival (DOA) estimation for co-prime MIMO radar is studied, and an estimation method based on unitary root-MUSIC is proposed. The co-prime MIMO radar has M-element transmit array and N-element receive array with Nλ/2 and Mλ/2 being the inter-element distances, respectively (λ means the wavelength, and M and N are co-prime integers). The algorithm firstly utilizes unitary transformation to transform the complex eigenvalue decomposition (EVD) into real-valued one, which can reduce the complexity. Thereafter, as the virtual elements generated by co-prime MIMO radar are not continuous, the sorting and zero filling operations are carried out to establish a standard polynomial root finding form. Finally, the DOA can be estimated by finding the roots of the polynomials. Due to the using of co-prime array for MIMO radar, the proposed algorithm can achieve much better DOA estimation performance and determine more targets than conventional methods using compact arrays.

The next-generation manufacture systems will deploy large-scale wireless sensor networks and super computers for autonomy. The large amount of information and complex decision support programs lead to new challenges on data storage and query. In this paper we analyze why the traditional RDBMSs are not suitable for the future WSNs and propose a tailored database storage engine SDORE to address the problem. SDORE firstly replaces the heavy concurrent mechanism with a lightweight timestamp-based protocol. Secondly it adopts an adaptive strategy to optimize the data distribution on hardware architectures dynamically. Experimental results show that the SDORE outperforms native RDBMS and gracefully adapts when the workload varies.

In response to the asymmetry transmit power problem in Wireless Sensor Networks, the concepts of quasi-hidden node and quasi-exposed node are introduced and an interference degree criterion (IDC) is designed to ensure the feasibility of concurrent transmission in wireless sensor networks. Simulation results show that, in comparison with 802.11DCF and SB-FSMA/CA, the power control strategy based on the proposed interference degree criterion not only improves the average network throughput but also reduces the average delivery delay.

In the indoor positioning system, serious multipath and ranging errors caused by non-line-of-sight phenomena become more significant. Thus, taking measures to reduce the influence of ranging errors on localization accuracy is a key issue in indoor positioning systems. In this paper, with respect to a wireless positioning system using ZigBee technology architecture, the trilateral measurement method, a localization algorithm based on distance measuring RSSI value and the Calman filter are optimized. This makes full use of the Calman filter's prediction, and by introducing a new factor in the prediction equation, errors are reduced, allowing more accurate location information to be returned.

Resource allocation in two-path relaying OFDM systems is investigated in this paper. In particular, it is first formulated as an optimization problem with the aim of total transmit power minimization, and is then decomposed into bit loading, subcarrier set allocation and source rate assignment issues. These issues are then solved separately, and a suboptimal algorithm is obtained. Simulation results demonstrate the effectiveness of the proposed algorithm under various system configurations through comparing it with the existing schemes with and without subcarrier pairing in traditional one-way relaying OFDM systems.

An optimal multiband spectrum sensing method based on the particle swarm optimization (PSO), which can jointly detect the primary signals in multiple different narrowband channels, is proposed in this paper. The algorithm enhances the achievable throughput of cognitive radio networks while protecting the interference of the primary users under a given level. Unlike the traditional algorithms to deal with this problem, the proposed method uses PSO algorithm to search the global optimal solution in whole feasible domain for any system configuration of cognitive radio networks. By operating directly on the objective of the optimization we show that the multiband spectrum sensing problem can be solved consistently without any limitations imposed on the secondary sub-band utilization and the per-band interference. Results show that the proposed PSO-based method is efficient and stable.

Spatial stepped-frequency multiple input multiple output (MIMO) array model is proposed to improve the resolution of MIMO radar. Two-sided correlation transformation (TCT) focusing algorithm and iterative power spectrum reconstruction (IPSR) algorithm are extended to this situation. TCT focusing algorithm estimates the direction of arrival (DOA) in reference frequency after focusing the signals of different frequency to the reference frequency, while IPSR estimates the DOA by reconstructing the power spectrum of different frequency signals iteratively. Simulation results show that the performance of IPSR algorithm is better than that of TCT focusing algorithm.

Aimed at satisfying the demand for mobile satellite service in China, the architecture and design methodology of radio resource control (RRC) module in a mobile satellite system are proposed and introduced in this paper. The system software hierarchy of the mobile terminal and the function components partition of RRC module are described at first. Then the hierarchical finite state machine methodology is introduced and adopted in the implementation to handle the high complexity and concurrence of RRC protocol. By using this methodology, the efficiency of protocol abstraction, function component partition and coding is improved significantly; the maintainability and evolutionary ability of the design are both evidently enhanced.

Broadband power line communication (BPLC) network is an excellent infrastructure for high speed data transmission. In this paper, the Orthogonal Frequency Division Modulation (OFDM) system in the Broadband power line communication and the effects of the cyclic prefix (CP) in such an OFDM system are investigated. An expression of signal to interference and noise rate (SINR) is presented as a function of delay, OFDM symbol length and CP length. Simulation results demonstrate that in order to achieve an ideal SINR, CP and the OFDM symbol should be long enough compared with the delay of the channel.

The security of a new certificateless signcryption by Liu et al was analyzed. The scheme was found to have defects such as the user's public key being replaced and a lack of semantic security. In view of this, an improved scheme was proposed. The improved scheme was proven to be confidential and existentially unforgeable under the determined bilinear Diffie-Hellman(DBDH) assumption in the random oracle model.

To solve the problem of efficiently and securely transmitting perceptual hash values in speech perceptual hashing authentication systems, a transparent and robust audio reversible watermarking algorithm is proposed in this paper. This algorithm, which is based on phase coding improved by bipolar quantization, guarantees its security by Logistic mapping. Experimental results show that the proposed algorithm has good reversibility, transparency, robustness and security, and has better comprehensive properties.

The cooperative multiple input multiple output (CMIMO) technology can significantly reduce energy consumption over conventional single input single input (SISO) technology in energy-constrained wireless sensor networks. In this work, we analyze the optimal number of cooperative nodes and modulation parameters to minimize the total energy consumption. We first establish the energy consumption model in broadcast phase and cooperative transmission phase considering circuit energy consumption. Then, a joint optimizing method is proposed to minimize the total energy consumption and obtain the optimal number of cooperative nodes and modulation parameters under the various broadcast distances and cooperative transmission distances. Simulation results show that energy efficiency can be greatly improved by joint optimization.

The original image transmission protocol based on WMSNs cannot meet the requirements for stable, reliable and real-time transmission because of the restricted transmission bandwidth and unstable communication link. To obtain abundant image information based on WMSNs, research on image transmission is necessary. In order to improve performance in terms of transmission reliability, transmission delay and node mortality, a multi-path crossed node rotation (MPCNR) protocol based on wireless sensor networks was proposed in this paper. The MPCNR protocol chooses multiple paths in parallel transmission expansion of bandwidth, puts forward the nodes with the same communication ability in each path, forming a cluster, and selects the most powerful node in the same cluster as a relay routing nodes to improves transmission stability and avoid large scale node death. A network simulation model by MATLAB was built to analyse the transmission reliability, the end-to-end delay and the number of surviving nodes. The simulation results show that, compared with the traditional image transmission protocol, the MPCNR protocol can improve performance in transmission reliability, transmission delay and node mortality. These findings are significant for image transmission based on wireless sensor networks.

k-anonymity is a widely used technology for privacy protection. In order to prevent attackers from digging out private information based on data published and his(her) background knowledge, a k-anonymity method is proposed, which uses the idea of clustering partition. Two different types of quasi-identifier attributes are individually subjected to a generalization process. The distance between tuples as well as the distance between a tuple and an equivalence class is also defined. In the process of clustering partition, some tuples are selected to constitute equivalence classes one by one, according to the principle of minimum distance value. k-anonymization is then completed, finally, by a separate generalization process. Through experiments comparing the performance of our method with that of an existing anonymization algorithm, EBKC, the effectiveness of the approach is verified.

Based on the existing classic matching method and its improved algorithm research, a new and faster character string matching algorithm named DCHS (Divide-Conquer and Hashing Strategy) algorithm is proposed in this paper. This algorithm incorporates the combined heuristics of divide and conquer, and preprocessed text and character string concurrent matching. Simultaneously, the hashing strategy is adopted at the juncture of each data block, in order to prevent leaky matching of the character string. Finally, from the specific analysis of simulation experimental data, DCHS is proven to perform better as compared to other algorithms.

A Remote Mobile Gas Monitoring and Power-off Control System (RMMPCS-IoT) based on Internet of Things is proposed, in order to help avoid gas disasters or accidents in underground coal mines. The key techniques and scheme of RMMPCS-IoT are given and analyzed, such as methane sensor and system architecture, communication and anti-jamming techniques, frequency offset compensation and CRC error checking and correction algorithm. The experimental tests are done in the working face entrance in the Xinjing coal from Yangquan coal industry (Group) Co., Ltd. in China, and the results show that the system not only provides a disaster prevention paradigm by remote mobile gas monitoring, but also has superior performance in terms of real-time (15ms) and accurate (99.99%) data transmission in working face as compared to other traditional gas monitoring systems.

Content-Centric Networking (CCN) has emerged as a promising communication paradigm to replace the host-based architecture with an information-based one for efficient dissemination of content. CCN has several special principles such as subscribe-driven, in-network caching, named content and content-level security. These features enable the content to be cached and retrieved from the nearby nodes, and it is unnecessary to build the communication connection with the content source. However, the mobility problems are not resolved sufficiently. It incurs the loss of packets and the longer handoff delay. This paper proposes distributed mobility management in CCN (D-CCN), which includes two mobility schemes: partially D-CCN (PD-CCN) and fully D-CCN (FD-CCN). Numerical results show that the proposed distributed mobility management schemes give better performance than the existing proposals in term of the total overhead during the handoff.

Vehicular Ad-hoc Networks (VANETs) is a self-organized network formed through mutual communication between vehicles and other vehicles or roadside units. Broadcast is an important protocol in VANET, but it may cause some problems. This paper proposes an efficient broadcasting algorithm that is adaptive to both a straight road and road intersection scenarios, and also has a high accuracy rate, low delay and low consumption. It uses a number of the neighbor nodes' driving direction and the distance from the neighbor to itself as the metric to select a relay node. The simulation results show that the proposed algorithm has several advantages: less rebroadcast packets, broader transmission range, and higher channel utilization.

Safety message transmission is a key issue in wireless networking as it concerns people's lives. The Enhanced Distributed Channel Access (EDCA) mechanism defined in IEEE 802.11e is used in a variety of networks as Medium Access Control (MAC) protocol which concerns the transmission of safety messages. However, due to the random nature of the default parameters of Contention Window (CW) in EDCA, safety messages would be deprived of their chance to access the channel due to low-priority traffic when the two collide. In addition, the priority classification in EDCA is universal and it is not perfectly appropriate for specific applications in some emergency scenarios. To address the above issues, this paper proposes a mechanism called Absolute EDCA (AEDCA). The word “absolute” refers to the guaranteed absolute priority status of safety messages. To ensure fast access and transactions while providing reliable service, the scheme adopts a reclassified priority category. Based on the new priority classification, an AEDCA algorithm to avoid the randomness of backoff's influence on high-priority traffic is proposed. Meanwhile, in order to accommodate and implement the algorithm, a CW parameter adjustment strategy is designed. Simulation results illustrate that the AEDCA scheme can provide more reliable transmission of safety messages and achieve better performance in terms of packet delivery ratio, delay and throughput.

The inherent characteristics of ad hoc networks have brought great challenges to intrusion detection technology. This paper applies the idea of deep learning to intrusion detection technology, and thereby proposes an intrusion detection method for ad hoc networks based on deep belief nets (DBN). Compared with traditional neural networks, DBN has the advantages of a multi-layer structure, and pre-training with the fine-tuning learning method. These advantages make DBN able to extract deep attributes of the training data, thus solving the problems of low training efficiency, being prone to falling into a local optimum, and the need for large numbers of tag data, that traditional neural network intrusion detection methods have. This method is thus effective for solving the complex ad hoc network intrusion detection problem.

In this paper, a new communication model to describe the controller placement problem of software-defined networks is proposed. Previous solutions to the problem only focus on the switch to controller latency, without paying attention to the latencies between controllers. In this study, both of these latencies were comprehensively studied, based on which the theory was raised. The simulation results show that the algorithm which suited the new model has better delays in most topologies.

In this paper, a 128-point FFT processor with high-speed and low computational complexity is proposed for multi-band orthogonal frequency-division multiplexing (MB-OFDM) based ultra-wideband (UWB) systems. A mixed-radix based FFT algorithm with low computational complexity is proposed to implement the 128-point FFT. To get high throughput, an 8-path parallel FFT processor is proposed. Based on the proposed FFT algorithm, the parallel FFT structure is implemented with a hybrid structure, which has high memory efficiency and low computational complexity. The evaluation results show that the proposed 128-point FFT processor can support high data rate transmission with low computational complexity and high memory efficiency.

The performance analysis of an Amplify-and-Forward (AF) cooperative communication network is presented. The system has M relays and the relay selection is based on outdated Channel State Information (CSI) of source-relay link. Asymptotical expressions of outage probability, channel capacity and Symbol Error Rate (SER) are derived. Analysis is applicable to independent identically distributed (i.i.d.) or independent none-identically distributed (i.n.d.) fading channels. Finally, simulations are carried out to verify the correctness of theoretical analysis and illustrate the effect of parameters on the performance. Results show that performance does not improve with an increase in relay number but relocation of the relay node can be regarded as a way to enhance performance.

The entity relation extraction in the Internet of Things (IoT) is one of the key issues in the smart interaction in the IoT. For natural language information in the IoT, current relation extraction methods based on tree kernel functions are widely applied because they allow the selection of different tree structures and kernel functions. However, these methods lack semantic features and contain excessive noise. These limitations result in low recalling rates. To solve this problem, this study suggests a relation extraction model based on semantic role labeling. This model adds semantic role information to tree structure nodes, removes redundant parts, conducts semantic expansion, and acquires a reformed shortest-path tree (SPT) as structural information. Experimental results show that adopting semantic role labeling and a reformed SPT improves the performance of relation extraction.

A new method of fast image encryption based on image characteristics and DES is presented. This paper introduces the basic characteristics of image, and analyzes the essence of DES. The image is first transformed based on rows and columns. Then a left-top part of the image is encrypted by DES. Most of the image data are encrypted using DES XOR operation. Experimental results show that this method has better safety, efficiency and is easily implemented.

The widespread popularity of private wireless TD-LTE network is recognized as an effective means for complementing optical fibers in Smart Grid communications. However, the TD-LTE network faces the challenge of blind coverage areas, such as underground and in buildings' corners. This paper presents a seamless relay mechanism for private wireless TD-LTE network in Smart Grid, with a detailed description of its network architecture, implementation topology, working mechanism and performance evaluation. The mechanism works at 470MHz and utilizes customized relay nodes to extend the coverage of TD-LTE network to those blind areas, thus achieving seamless communication for power distribution, metering, etc.

Forwarding lookup in the open flow switch can be done for each arriving packet by every switch in path. In view of the possible resource shortage in the existing SDN technology; this paper describes a fine-grained OpenFlow multiple-table pipeline architecture that efficiently stores the flow table in the TCAM memories. Simulations show that the strategy reduces the TCAM usage for the multipletable mapping scheme [1] by 14.3%, which is important for scalable designs of OpenFlow data planes.

This paper introduces a new reliable transport protocol, called Coded Cubic, which combines network coding with Cubic TCP, with retransmission schedule and the mechanism for congestion control adjusted appropriately. According to the characteristics of Coded Cubic, redundancy parameter adjustment mechanism is proposed to adapt to the changing environment. Coded Cubic was implemented in Linux kernel with small changes in the existing implementation of standard TCP. It was then tested in the real environment. The results show that Coded Cubic has a great performance improvement compared with standard Cubic in lossy wireless network, besides which, Coded Cubic is also friendly with standard TCP and has good fairness between Coded Cubic flows.

Based on the demands of multi-missile cooperative combat and the characteristics of Wireless Sensor Network (WSN), this paper proposes a novel cooperative combat model of multi-missile formation which establishes internal data links in the form of WSN. In the proposed model, WSN nodes are not only used to transmit real-time tactics information but also monitor the environment status such as temperature, humidity, air pressure and so on. This paper also gives the network topology of WSN and the implementation of the model. As network delay plays a very important role in military network, simulations revealing the influence of WSN network delay on our model under the guidance law of some certain missile are conducted. Simulation results show that our model under the given guidance law can tolerate a delay of 50ms. However, for delays lager than 60ms, multi-missile cooperative formation begins to diverge, and missiles are not able to achieve the scheduled formation.

In order to solve the problem of high-speed sampling in OFDM based ultra wide band (UWB) systems, this paper provides an analysis of the applicability of two existing compressed sampling methods, namely random modulation (RD) and parallel segmented compressed sensing (PSCS), for analog signals. The optimized orthogonal matching pursuit algorithm is used for the known sparsity avoiding iterative operation. Simulations show that the PSCS scheme can reduce the sampling rate in OFDM-UWB systems effectively as compared to RD. The system based on PSCS achieves a performance significantly better than that of RD.

In order to provide seamless mobility support for differentiated content in mobile NDN (Named Data Networking) environment, we propose a differentiated content mobility support approach, dubbed DCMA. Firstly, we induce a route-able ID (IDentity) that is structurally similar to the content name, and add an Optional field to the original NDN packet. Then, DCMA can both increase the addressing efficiency of INTEREST packet, and maintain the routing scalability of NDN. Besides, we extend the basic functionalities of the NARs (NDN Access Routers), group the content into three classes, and further set differentiated forwarding priority level for differentiated content. After that, DCMA can both resolve the Source mobility problem effectively, and provide differentiated handoff experience level for differentiated content. Moreover, we compare the handoff performance of DCMA and other Source mobility support approaches via simulation investigation. Relevant results indicate that, DCMA can provide lower handoff cost, as well as shorter handoff latency during the handoff process of the Source.

In this paper, the problem of analysing adaptive exponential synchronization in pth moment is considered for neutral-type neural networks with time delays and Markovian switching. By utilizing a new non-negative function and the M-matrix approach, several sufficient conditions to ensure the adaptive exponential synchronization in pth moment for neutral-type neural networks are derived. Via the adaptive feedback control techniques, some suitable parameters update laws are found. Finally, a numerical example is provided to illustrate the effectiveness of the M-matrix-based synchronization conditions derived in this paper.

Optimizing routing paths improves the network's topological properties and performance, and helps balance the network's energy. Traditional network routing algorithms use the energy balanced ring routing algorithm, which causes an uneven consumption of energy throughout the network. This paper thus proposes a method of optimizing network routing paths based on an improved ant colony algorithm with constraint feedback. First, a network model is designed, and its topology is established. The robust coefficients are determined, and route choices are used to update the GRAEB routing algorithm. Using the region segmentation method, the confidence interval of cluster routing task's random distribution is obtained. Through the ant feedback constraint, the probability of information being correctly transmitted is increased. According to Bayes' theorem, route node localization and saving of route location reliability recursive algorithm, network routing is optimized. Simulation experiments show that the algorithm can effectively increase the probability of information being transmitted correctly on the network, with transmission being almost distortion-free. As the number of routing hops increases, the advantages of this routing algorithm become more apparent, improving the quality of the information transmission.

Orthogonal frequency division multiplexing (OFDM) technology is core to the field of wireless communications. In order to optimize the resource allocation and minimize the transmitted power in the OFDM system, this paper proposes a hybrid optimizing algorithm which combines the advantages of both the tabu search algorithm with genetic algorithm. In the proposed algorithm, the tabu search is used to form a new crossover, and the better individual is added to the initial population according to its fitness. This improves the algorithm's climbing ability, and also speeds up its convergence. Simulation results show that the algorithm proposed has superior effectiveness and reliability as compared to other improved genetic algorithms.

This paper presents a new wideband spectrum sensing method based on the rank criterion. This proposed method first divides the sample covariance matrix of received signal into the “ideal” matrix, having a rank of q, and the “perturbed” matrix. The rank criterion function is then used to search for the optimal q value, which is used to determine the numbers and the locations of the occupied channels. Owing to the method repeatedly using matrix eigenvalue decomposition in the formula derivation, computation time is increased, making the method unconducive to the real-time processing of the algorithm. Thus, the algorithm was improved upon by using the signal sampling power to approximate the eigenvalues of the sample covariance matrix. This greatly improved the proposed method's operation speed. Simulation results verified the effectiveness of the proposed method.

The conventional group signature scheme allows a group member to anonymously sign a message on behalf of the group, but only the group manager can identify the signer. Sometimes, a group member may send a subliminal message to the special receiver on behalf of the group, while others cannot obtain this subliminal message but can verify this signature's validity. In this paper, we extend the conventional group signature and propose a novel signature type, namely the group signature scheme with subliminal channel, to realize this functionality. In this scheme, the size of signature and public key is independent of the size of the group.

In this paper, we consider the sensing order and sensing stopping problem arising from the opportunistic spectrum in cognitive networks. Due to the sensing cost, a secondary user (SU) needs to find an available channel with as small a cost as possible. On the other hand, the SU hopes to obtain sufficient information about these spectrum holes such that it can attain as much utility as possible. The paradoxical target calls for a delicate mechanism to minimize the trade-off between exploitation and exploration. Specifically, we consider two different scenarios: homogeneous channels and heterogeneous channels, and propose an easily implemented heuristic policy to achieve the twin goals of obtaining an available channel and obtaining sufficient information about those spectrum holes. Extensive numerical experiments also demonstrate the effectiveness of the proposed heuristic algorithm.

This paper aims to improve the safety of chaotic image encryption algorithm. To achieve this goal, a new hyperchaotic system was put forward, and its nonlinear dynamics performance was analyzed to prove its excellent chaotic characteristics, including its Lyapunov exponents, phase diagram, bifurcation diagram and so on. The hyperchaotic system was applied to an image encryption algorithm, forming a hyperchaotic image encryption algorithm. A performance analysis was conducted on the algorithm, including key space analysis and efficiency analysis, key sensitivity, correlation analysis between adjacent pixels, and gray histogram analysis. The algorithm was also compared with other chaotic image encryption algorithms. Theoretical analysis and simulation results showed that the improved algorithm is not only able to resist the chosen plaintext attack, but can also obtain better cryptographic properties.

To ensure that information is transmitted correctly and rapidly in the complicated communication system of the Internet of Things (IOTs), there is a need to equalize the signals blindly, quickly and precisely. This has driven intensive research into blind equalization technology. When studying a new algorithm or designing a suitable blind equalizer, evaluating the properties is, though important, also costly, repetitive and time-consuming. Hence, a simulation platform for blind equalization technologies of communication systems was developed in this paper, based on the Mathworks^® Matlab 2012a GUI. This software platform would be an easy-to-govern and operational platform, and be helpful for researchers and engineers to research on or choose blind equalization methods.

The past few years have seen an increased interest in the potential use of wireless sensor networks (WSNs) in applications. Unreliability and a dynamic nature are frequently present in the field of WSN, making anomaly detection necessary. Although events are often functions of more than one attribute and the energy in sensors is limited, the combination of data fusion and spatiotemporal correlations can overcome these limitations effectively. In this paper, we propose a spatiotemporal correlation-based anomaly detection model to differentiate normal and abnormal events in WSNs. The update phase occurs when abnormal events are detected. We demonstrate the usability and advantages of applying the spatiotemporal relevance in anomaly detection. Experimental results indicate its high performance in handling multi-dimensional sensor data.

In the future, the data center of the network is urgently needed for the support of a router device which has the security isolation and virtual nature. The virtual router based on the security isolation can construct a virtual network on a physical network, which has the ability to improve the security of data transmission and the ability to prevent the transmission from the virus. Compared with the traditional router, the security isolation based on the virtual router has the characteristics of security isolation and virtualization.

Cloud storage has seen an increasing trend with the development of social networks, but its security remains an important problem to be solved. In this paper, a new encryption scheme based on dynamic attributes is proposed to solve the problem in the attribute based encryption scheme. In the scheme, a data encryption access control strategy is generated by the sender attributes according to certain logical relationships. Additionally, an access control tree structure is used to describe the access control policy. Only when the attribute set of receiver meets the access policy can the data be decrypted; to achieve this, the access control tree structure is dynamically adjusted simultaneously with changes in the attribute set of sender.

In response to the problem of inconsistent control caused by the inevitable delays between the controller and switches in the software defined networking (SDN), the average delay between controller and switches in SDN are obtained through controller-to-switch message through Openflow protocol, and a consistent update scheme based on shortest average delay (namely CUSBSAD) for control logic in SDN is designed. In addition, an objective optimization model based on the shortest average delay of nodes is constructed. This model is then used to find the minimum-delay route while retaining the logical consistency in the SDN network. The simulation results demonstrate that the proposed scheme is feasible and effective.

To resolve the problem of unbalanced energy consumption in heterogeneous electricity-information acquisition networks, an energy-balanced link scheduling algorithm based on clustering is proposed. Combined with the characteristics of electricity-information acquisition system, the algorithm determines the optimal number of clusters by minimizing the energy consumption of the whole network. Based on the distribute energy efficient clustering algorithm (DEEC), the cluster heads are selected by considering the residual energy and location of nodes. Further, the probability that the slave nodes communicate with the cluster head in a single-hop mode is determined by balancing the energy consumption innermost and outermost. Simulation results show that the link scheduling algorithm can balance the network load and prolong the life of network.

In the past decade, industrial wireless technology and sensor technology have seen great development, such that the advantages of wireless sensor networks (WSN) in industrial applications have become increasingly obvious. Currently, the issue of how to design and build a stable and reliable industrial wireless sensor network remains an important research area in this field. In this paper, the operational information of each industrial wireless sensor network communication node is collected as a reliability test, and the information source is analyzed and evaluated. A reliability evaluation model is constructed based on factors affecting the reliability of industrial WSNs and a reliability assessment which uses traditional data analysis and mining methods. By using effective reliability evaluation strategies and methods, the reliability assessment's accuracy is guaranteed. As for the performance indicators of an industrial WSN's reliability, the impact of the protocol layer on network reliability was investigated. Based on this framework, the reliability index model and reliability evaluation method were studied.

Enhancing the reliability of communication links is essential to network design. Generally, one or more redundant links are designed between switches. Adding redundant links can ensure proper communication link, but may also lead to loops, causing broadcast storms, multiple frame copy, and MAC address table instability problems, for example. MSTP is a new spanning tree based on STP/RSTP. It not only inherits the fast forwarding mechanism of RSTP port, which can eliminate network loops and has the function of link redundancy backup, but also solves the problem of different VLAN having to run on the same tree in RSTP, and achieves load balance by forming multiple spanning trees. This paper mainly introduces the principles of MSTP and the optimization of the network to achieve network load balance through the MSTP protocol.

Digital image encryption is especially important in body area networks (BANs) applications since the image may contain some private or sensitive information. Past encryption methods have the disadvantages of a small key space and a low resistance to attack. In this paper, we propose a new encryption algorithm based on discrete wavelet transform (DWT) and multi-chaos. The image is first decomposed by DWT, and is then processed by multi-chaos matrices, which are deterministic, pseudo-random, and sensitive to initial values. The experimental results indicate that the proposed algorithm has a large key space, high key sensitivity and excellent resistance to attacks.

Geomagnetic sensors have recently been utilized for road traffic measurement due to their low cost, small size and low power consumption, etc. During system operation, the geomagnetic field is often quite unstable due to environmental changes, possibly degrading measurement accuracy. This paper focuses on the development of an environment-adaptive road traffic measurement algorithm on single wireless geomagnetic sensor node. In order to reduce the impact of unstable environments, its state machine for vehicle identification was designed to be able to perform self-adjustment according to background geomagnetic field changes. Experimental results show that the proposed algorithm can accurately report the number of passing vehicles traveling at low or high speeds in one lane, and will not be affected by vehicles running in adjacent lanes.

A new cooperative spectrum sensing scheme based on the improved particle swarm optimization (PSO) algorithm is proposed for cognitive radio (CR) in this paper. In the proposed method, the improved PSO is utilized to obtain the optimal weight vector to maximize the probability of detection by changing the inertia weight dynamically in each iteration. The proposed method performs better in convergence than the method based on the traditional PSO. Furthermore, it can get better detection probability than the modified deflection coefficient (MDC) method. The simulation results verify the efficiency of the proposed method.

Authentication is the primary issue taken into consideration with regards to network security, and is the basis for increasing the practicality of wireless networks. A good authentication system can greatly improve the wireless network's social efficiency and solve security problems, such as identity authentication and privacy issues. Fingerprint identification can be effectively applied in identity authentication, but there is a high rate of false rejection and false acceptance in traditional fingerprint identification methods[1]. An adaptive ant colony algorithm was thus presented in this paper, by which the threshold was set. The image segmentation fingerprint sample images were sent to some blocks in the client, and were sent to the server for matching. The experimental results show that this system can effectively improve the rate of remote fingerprint recognition.

Previous research has shown that the search performance of Trie-based algorithms can be improved by adding on-chip Bloom filters. The Bloom filter can identify the membership of a node in an off-chip Trie, and the number of off-chip memory accesses is reduced. But the Trie-based structure has the shortcoming that it is difficult to delete or insert nodes once the Trie has been constructed. In this paper, we propose a new method of utilizing a counting Bloom filter for the IP address lookup of longest prefix match which can make some operations with the Trie nodes. Simulation results show that the best matching prefix can be found with limited off-chip access and much better performance of search can be achieved in our proposed method.

Big data often calls for the further analysis and organization of data such that valuable information can be retrieved and organized for both parties to achieve their goals. A typical example pertaining to the development of big data is the network legal database. The establishment of case databases has always been an important method of assisting legal research. In fields dominated by the common law system, developing trends of legal rules could be abstracted from the classification of large numbers of cases, making the network case database essential for practitioners and scholars. Starting with an analysis of the big data era of networking, this paper focuses on establishing a case database in international investment arbitration to analyze the possibility of promoting research into international investment law system. This paper contains three parts. The first part introduces the status of establishing network case databases in international investment arbitration. The second part explains the positive impact of the case database construction on both parties and arbitrators in international investment arbitration. The third part analyzes the possibility of further development of network case databases from the perspective of the impartiality of arbitrator.

This article introduces the high-rise building fire escape ZigBee positioning systems and data transmission optimization method. An analysis of the ZigBee routing path was carried out based on the characteristics of high-rise building fires and extremely large numbers of people. In order to address the problem of delays in transferring data, a large amount of data was used when starting the optimization of the routing path.

This paper describes the characteristics of typical powerline carriers and micro-power wireless communication in local AMR system. In order to solve the problem of low acquisition success rate, this paper presents a dual-channel self-organizing network model in local AMR system, based on powerline channel and micro-power wireless channel. In a self-organizing AMR network, relay routing selection is a crucial challenge in cooperative communication. Thus, a load-balancing dynamic source routing (LDSR) algorithm was designed, which is based on the activity of the meter node, and which uses the relaying number in each node and its neighbor nodes to indirectly evaluate the activity of each node. If some node's activity exceeds a certain threshold value, the cost of the node to relay packet is increased. Compared to the pure DSR algorithm, the LDSR algorithm effectively reduces the maximum number of relay packets among all nodes. This can shorten the meter reading period and increase network throughput. The superiority of this proposed routing scheme was verified through a simulation.

Wireless Body Area Networks (WBANs) are envisioned as a key enabling technology for the next-generation pervasive healthcare systems. Characterized by limited energy and computational resources, inter-user interference deteriorates reliable data transmission when multiple WBANs are transmitting simultaneously on the same channel in close proximity, making it one of the greatest challenges. In this paper, we propose a novel distributed adaptive scheduling scheme to reduce interference among co-existing WBANs. The basic idea of this scheduling scheme is to avoid the overlap of active beacon period of neighboring WBANs. The performance of the proposed scheme was compared with schemes based on IEEE 802.15.6 using an OMNET++ simulator. Simulation results show that the proposed scheme performs better in terms of packet delivery ratio, energy consumption and delivery latency than the schemes based on IEEE 802.15.6.

Public transportation lines offer a convenient mode of travel when efficiently organized. This paper studies the recommendation of new public transport routes by using natural language processing methods to mine vast amounts of unstructured data based on the Beijing bus forums, and create citizen's public transport travel requirements. It also applies computer techniques and mathematical models to the adjustment and optimization of original advice of public transport route planning and into economic efficiency forecast on new public traffic lines. Through filtering and sorting, the list of recommendations for Beijing public transport route optimization is obtained, and the results could be shown with a visualization method. Finally, empirical studies on real-world data demonstrate that the proposed method outperforms benchmark methods by a significant margin.

Pico-cell technology is regarded as a promising technology for achieving a homogeneous user experience and maximizing cell capacity. However, Pico-cells with full frequency reuse introduce strong Cross-Tier Interference (CTI) in uplink thus degrading the system performance. Traditional LTE-A uplink power control scheme only applies standardized Open Loop Power Control (OLPC) while LTE-A uplink needs Closed Loop Power Control (CLPC) scheme to mitigate the interference. Further optimization of the system performance can be via CLPC scheme. In this paper, the CLPC algorithms based on path loss, Inter-Cell Interference (ICI) and CTI are proposed to coordinate the interference of Heterogeneous Networks (HetNets). It is demonstrated by system simulations that the proposed power control schemes take into account the efficiency of battery power utilization, and can also significantly improve the cell edge and average throughput.

TD-LTE (Time division duplex-long term evolution) is a mainstream standard of the fourth generation mobile communication led by China. In this paper, a TD-LTE base-station signal is proposed to achieve passive detection of targets as external radiation sources. First, it is proposed that the detection distance of the passive radar can be enhanced using multi-static radar according to the characteristics of TD-LTE. The processing of passive radar signal of TD-LTE is then given. By reconstructing the reference signal according to the 3GPP standard, pure multi-base station signals can be attained without demodulation. Finally, the characteristics of the ambiguity function of OFDM (orthogonal frequency division multiplexing) signal is analyzed. The reasons and positions of side peaks are deduced, and the ambiguity is resolved via frequency domain synthesis. The availability of the method proposed is proven using actual signals.

The sensor management algorithm based on PHD (Probability Hypothesis Density) proposed by Mahlar consider sensors' FoV(Field of View) as a circle, which can acquire measurements from targets in 360 degrees. But the FoV of some modern sensors such as phase-array radar is not omni-directional; it can only detect targets from a fixed direction. To solve this problem, this paper proposes a method to improve the FoV by combining the directivity function of the antenna with the FoV function. This improved FoV function can adapt to changes in modern sensors' FoV. Simulation results show that the proposed FoV function can reflect the character of sensors better and achieve sensor management more effectively, and also acquire higher target tracing accuracy.

With the rapid development of Ethernet and IP technology, digital audio broadcasting over IP has become an urgent problem for radio stations. This paper analyses the problems facing real-time transmission of digital audio over IP networks, and discusses the corresponding solutions, focusing on the introduction of AoIP technology. The application scheme of the actual solution is also given. The solution also has a large number of applications in actual projects, making this paper significant for future reference.

The concept, the data format and the locating principles of the iBeacon were introduced in this paper. The differences between BLE4.0 and normal Bluetooth were explained. Additionally, the locating methods of “single point, two points and multi points” were proposed. The advantages and disadvantages of the iBeacon in the aspects of locating and application scenarios were analyzed. In the end, the applications such as the mobile e-commerce O2O, mobile payment and real-time communication were analyzed.

In this paper, the Quadrature Kalman filter (QKF) algorithm of nonlinear systems is studied in-depth, with its merits and drawbacks being analyzed. A suboptimal fading QKF algorithm (SFQKF) based on Strong Tacking Filter(STF) is also proposed to adjust the covariance matrix of state prediction error, the covariance matrix of prediction error, and the cross covariance matrix between the state prediction error and the measured prediction error in real time through the time-varied suboptimum fading factor, which can adjust the gain matrix of filter in real time. Moreover, the derivative process of suboptimal fading factor is given. The mechanism analysis and emulation experiment of this algorithm show that SFQKF algorithm, which inherits the excellent performance of Strong Tracking Filter (STF), can overcome the defects of QKF algorithm and have stronger ability to track the states with abrupt changes. Compared with QKF algorithm, the stability of FQKF algorithm is improved by 14.9%, and the amount of calculations required is moderate.

One of the fundamental requirements for energy-constrained wireless sensor networks (WSN) is to reduce the power consumption and prolong the network lifetime. To deal with the problem, a mobile agent-based clustering management model is proposed, which adopts the distributed architecture and realize data processing in local nodes. Based on proposed model and traditional client/server model, we present the comprehensive performance comparison and analysis. Furthermore, we develop an algorithm to calculate an optimal power management scheme applied to mobile agent-based clustering WSN. Simulation results indicate a remarkable performance improvement by using the proposed model and the optimal power management scheme. At the same time, the simulation study also provides the valuable guidance for the WSN designers.

Air breakdown is a limiting factor in the design of high-power microwave systems. However, air breakdown is a probabilistic event when external conditions are invariant. To solve this problem, a novel model combining the average electron generation rate model and avalanche breakdown model is proposed in this paper to simulate the probability distribution of high-power microwave breakdown in air. The air breakdown probability distribution is simulated under conditions similar to the experimental ones, and the simulation results are in good agreement with the experimental data.

Occasionally, it is not possible to debug an application that contains a specific template in the development environment. While the SideLoading function can overcome this, the use of this feature poses great potential safety risks to application website sets if not appropriately applied. Many developers thus face a conundrum in deciding whether to enable this feature or not. This paper explores the characteristics and working mechanism of SideLoading applications in depth, proposes distinct boundaries about when and where this feature should be turned on or off, and offers a detailed code to illustrate how this function can be enabled and disabled in accordance with demand.

China's rapid economic development has also led to increased traffic jams, environmental pollution and traffic accidents due to increasing car ownership. This has made traffic management more difficult. To increase transportation efficiency, reduce environmental pollution and reduce energy consumption, an Integrated Transport System can be formed using an Intelligent Transportation System. In this paper, the current traffic situation in China is first introduced along with the functions and structures of the Intelligent Transportation System. Advanced foreign Intelligent Transportation Systems are then introduced, followed by an analysis of the country's current traffic situation. Finally, the paper lists the framework of the Intelligent Transportation System and its proper solutions suitable for the country.

This study aims to master the changing of vehicles' diesel engine and supercharger work load, and to find the regularities within. Besides forming the basis of new-type diesel engines and supercharger's endurance and reliability design, it can also provide an important basis for the diesel engine which is on active duty as well as supercharger's life prediction, extension and reliability test. This article focuses on specific types of armored vehicles and developed the power union load testing system. It can provide technical support for further accumulating and formulating the load spectrum of vehicle and supercharger.

Demand side management is an effective method for conserving energy and reducing emissions. In this paper, power big data research and its application in smart grids is discussed. Using information and communications technology, a c-means clustering algorithm was made as the core, after which it was combined with cloud computing technology and an electricity demand response model to establish the constraint equation. This model was then used for a residential electricity data classification task. Taking 200 randomized sampling users, three user groups were obtained. For the first and third groups, orderly electricity consumption was carried out, and the electricity load was reduced by 5%. The calculations demonstrate the validity of our model and algorithm.

With the growing popularity of mobile Internet, attacks from mobile users have increased tremendously, causing difficulties in providing reliable and ubiquitous services for end users. Mobile users can attack network elements by sending malicious packets towards the same or different destinations. Based on identifier locator separation mapping based mobile Internet and Reputation Level (RL)-based access scheme studied in our previous work, we propose a source-oriented cooperative approach (SoCA) for mitigating DoS/DDoS attack in identifier locator separation mapping Internet with GPRS access. In particular, SoCA can trace the potential source by using IMSI, and works cooperatively with the network unit in GPRS access networks. SoCA is analyzed theoretically by proposing an analytical model for traffic acceptance probability, which is related to user and service visit behavior. Numerical results show that the attack can be effectively eliminated by adapting the traffic acceptance probability to the users and service visit behavior.

Long Reach Passive Optical Network (LR-PON) is the new trend in Passive Optical Network (PON). It can cover a wider distance and serve more users while reducing the complexity of the network. With the extended coverage in LR-PON, the propagation delay is 10 times larger than that in EPON. Dynamic Bandwidth Allocation (DBA) algorithms developed for EPONs are not properly fit for LR-PONs. Therefore, novel DBA algorithms have been proposed recently for LR-PONs. In this paper, we present an overview of several DBA algorithms developed for LR-PONs, and compare briefly the fundamental properties of each algorithm. In addition, an OPNET-based simulation platform has been developed to evaluate the performance of DBA algorithms in LRPONs. We investigate the performance of different DBA algorithms for LR-PONs with respect to average packet delay and channel utilization thoroughly by extensive simulations. The simulation results can provide a great insight in the design of DBA algorithms for LR-PONs.

The first application of singular value decomposition(SVD) to digital watermarking in 2002[1] has attracted scholars' attention ever since. Currently, because of the stability of singular value decomposition and the algebraic characteristics of images, many robust watermarking algorithms based on singular value decomposition have been proposed. This paper introduces the application of SVD to a digital watermarking algorithm. Through four experiments, the paper shows that the SVD-based algorithms evoke problems of uncertainty, as copyright ownership cannot be determined.

This paper first analyzes the shortcomings of current Hadoop systems used for managing big data from electric power systems, before proposing an index management scheme for electric cloud data based on Hadoop to overcome the problems associated with big data storage and the query model in a Hadoop framework. Big data from electric power systems can be classified as information data or massive data, according to its storage space and access frequency. Based on the characteristics of different data types and combined with the characteristics of an Hbase database, a new index system and query solution scheme for electric big data is proposed. Using the divide and conquer strategy, the inverted index is built on information data by Zipf's law and weights. By using index cluster and Hbase cluster to construct the index of different granularity on massive data, the stability and reliability of the system can be improved.

Concentrating on the problem of approximating the desired magnitude response of a filter by designing a linear-phase FIR filter, this paper derives the formulas to obtain the filter coefficients of type I, II, III and IV linear-phase filters based on the weighted L2 norm. Through several numerical examples of low pass filter, band pass filter, high pass filter and band stop filter, it shows that the filters designed with method in this paper are of less weighted L₂ errors than other filters designed by using Kaiser Window, equiripple approximation theory and so on.

Uygur language is an agglutinative language with words as its basic unit. Because of the different positions in the word, the letters have different writing deformation. This paper analyzes the current two concepts of Uygur handwriting recognition, discusses the advantages and disadvantages of the two concepts, proposes an effective method of segmenting first and then recognizing, and establishes preliminary models for the post processing.

With software's growing scale and complexity, software quality assurance has become the key problem facing the software industry. Thus, the significance of software testing cannot be understated. Automated testing technology is the primary method of software testing used enhance testing efficiency. In this paper, an automated test proposal based on AutoRunner and TestCenter is introduced. TestCenter manages the whole test process using the test requirements and testing plan. Moreover, AutoRunner enhances test script reusability by means of parameterization and the use of checkpoints. Finally, the automated test scheme is introduced with a tested CRM system.

The concept and situation of O2O are introduced in the paper, after which the advantages of O2O were discussed. The paper then presents the realizable scheme of O2O based on iBeacon and illustrates the implementation steps. O2O's current problems were analyzed, with the ultimate result of personalized services or products for customers being proposed as the development direction of O2O in the future. The basic implementation process and framework for this are proposed.

This paper introduces the design and implementation of an embedded video monitoring system based on S3C2440 and FFmpeg. The whole system is realized based on the embedded platform. For the hardware, S3C2440 of Samsung Corp is used as the core processor. A 5000000 pixels USB camera whose driver software is not required is used as the video acquisition equipment. A PC is designed as the client, mainly used to receive and decode the video stream, and for its display. As for the software, video acquisition is realized through V4L2. The encoding and decoding of the video stream is realized through FFmpeg. Finally, we test the system's performance in different transmission mediums, and analyze the test results, including frame rate, bandwidth and time delay.

As the primary standard for exhibiting information in the network era, HTML5 is applied in almost every system platform and terminal equipment due to its versatile and cross-platform features. Therefore, it is of great practical significance to explore the function of HTML5. In this era of traditional internet shifting into mobile internet, geographical location-based services have bright prospects and significant commercial value. With its geolocation module, HTML5 can definitely be used for orientation-related functions. This paper probes into the geolocation module of HTML5 and offers detailed code on how to use this module in mainstream electronic maps to achieve terminal positioning services.

Although more and more organizations are adopting mobile computing devices such as smartphones and tablets, not all companies are equally profiting from the integration of mobile information systems (IS) and information technology (IT). This is surprising since the benefits of mobile IS/IT adoption cited in literature, such as productivity and motivation increases, are rather generic and should – in theory – be measurable in every instance of mobile IS/IT adoption. We address this issue by developing a conceptual model of the benefits of mobile IS/IT adoption and a number of key moderators, which we believe may offer an explanation why some companies are failing to reap these benefits. The model is based on a deductive-inductive research approach, combining an extensive literature review and 17 interviews with mobile computing experts in major German and Swiss public corporations. The model therefore integrates insights from theory and practice to arrive at a more holistic understanding of our research topic.

The orthogonality of sub-carriers is broken and the system's capability is decayed by Doppler frequency shifts in long term evolution (LTE) systems. This paper thus investigated the impact of Doppler frequency shifts on such LTE systems. First, the power leakage of the adjacent sub-carriers' single sub-carrier signal caused by the frequency shift is calculated in Quadrature Phase Shift Keying (QPSK) modulation. Then, the influence of the Doppler frequency shift on the Carrier-to-Interference Ratio (CIR) and the power of Inter-Carrier Interference (ICI) are analyzed. The results indicate that the parameters of an LTE system can well withstand the Doppler frequency shift caused by high speed movement of the mobile station.

In this paper, we present a the design of a parallel HEVC decoder based on a Multi-core platform. The proposed method groups HEVC decoding modules into entropy decoding and CTU-row decoding parts for optimal parallelization, considering the characteristic of all parts. Coding tree unit (CTU)-level 2D Wavefront is employed for the CTU-row decoding part. To decrease the delay between the entropy decoding and the CTU-row decoding, task level parallelism (TLP) is also used for these two parts. Compared to sequential execution, the experimental results show that our proposed method achieves an average of more than 6.7 times speed-up for 1920x1080 video sequences without any encoder parallel tools such as Wavefront Parallel Processing (WPP) coding and picture partitioning with tile and slice segments.

In this paper, we propose an impulse noise removal algorithm, which can realize the elimination of the impulse noise in an image effectively even though these noises are on image edges or details. The algorithm introduces a statistic, visual perception outlier measurement (VPOM for short), to identify the impulse noise in an image. Once the noises are identified, noise candidates are restored by a nonlocal edge-preserving regularized filter. Extensive experimental results indicate that our algorithm provides a significant improvement over many other existing techniques.

In the last 50 years, the feature size of the fabrication process for integrated circuits has continuously shrunk, corroborating Moore's Law that the feature size will be halved every 18 months. Recently, however, the problems caused by highly integrated CMOS devices such as large leakage current, high temperature when operating and high energy consumption became a huge barrier impeding the development of integrated circuits. In 1998, CNFET was proposed, and its good electrical characteristics attracted a lot of attention. CNFET is the best potential device to replace traditional CMOS devices. In this paper, a CNFET based full adder with mirror structure was thus proposed, and a comparison between CNFET full adder and conventional CMOS full adder was made.

The following sections is included:

• Author Index